>> >
>> >I need to produce a conus map with some cities and their
>> >surrounding points marked on the map. I have the city locations
>> >in lat/long but the surrounding points are in RUC20 grid points.
>> >[ie subscript indices]
>> >
>> >I was just wondering if someone out there has already done
>> >something similar and can provide an NCL sample script.
>> >
>> >Thanks in advance.
===============================================================
>
>Here is a sample data file:
>city % lat long x0 y0 x1 y1 x2 y2 x3 y3
>--------------------------------------------------------
> ABQ 5.82 35.05 106.62 111 86 111 87 112 86 112 87
> ALB 6.16 42.75 73.80 253 134 253 135 254 134 254 135
> ATL 8.98 33.75 84.38 212 78 212 79 213 78 213 79
>
>I want to mark each city location and its surrounding grid
>points on the map with the city's name and the % value.
>The xs and ys are RUC20 grid point locations. Will NCL
>convert the grid point pair into lat/long?
>
Basically, the sequence is the following:
[1] Read the ascii file. The 1st two lines [ie, rows]
are header lines. The rest of the ascii file contains
the data. The data are one column of ascii and the
rest numeric.
[a] use the "readAsciiTable" function located in
contributed.ncl and the standard "asciiread" function
[b] extract the pertinent info
[2] Read appropriate RUC GRIB file that contians the
appropriate lat/lon grid coordinates
[3] Generate plot
[a] generate map background
[b] Use "gsn_polymarker" to generate a polymarker to indicate
the city's location (filled circle used)
[c] use "gsn_text" to generate the city's 3 alphabetic identifier
[d] use "gsn_polymarker" to generate grid point locations
Please look at the following:
http://www.cgd.ucar.edu/csm/support/CSM_Graphics/polyg.shtml
http://www.cgd.ucar.edu/csm/support/CSM_Graphics/text.shtml
A sample script is attached.
--
One issue: are the given subscript indices 0-based like C/NCL
or are they 1-based like fortran. If 1-based, you
must subtract 1 from each subscript.
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl" load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl" load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl" begin ;------------------------------------------------------------- ; Read ascii file ;------------------------------------------------------------- dir = "./" fil = "city.ascii" ncol = 11 ; # col of numeric data nhead = 2 ; # header lines
; read all rows as string s = asciiread ( dir+fil, -1, "string") nrow = dimsizes(s) ;print (s) ;print (s(nhead:)) ; convert to character and create city string c = stringtochar(s(nhead:)) ; skip 1st two header lines city = chartostring(c(:,1:3)) print (city) ; read all numbers as float x = readAsciiTable( dir+fil, ncol, "float", nhead) printVarSummary (x) dimx = dimsizes(x) npts = dimx(0)
; For clarity assign members of x to separate variables pc = x(:,0) ; % latc = x(:,1) ; city lat lonc = -x(:,2) ; city lon (make W)
ix0 = floattointeger(x(:,3)) iy0 = floattointeger(x(:,4)) ix1 = floattointeger(x(:,5)) iy1 = floattointeger(x(:,6)) ix2 = floattointeger(x(:,7)) iy2 = floattointeger(x(:,8)) ix3 = floattointeger(x(:,9)) iy3 = floattointeger(x(:,10))
;------------------------------------------------------------- ; Read RUC file ;-------------------------------------------------------------
diri = "/cgd/cas/shea/celiaChen/" fili = "ruc2.bgrb.20020418.i12.f00.grb"
f = addfile (diri+fili, "r") lat2d = f->gridlat_252 ; [gridx_252 | 225] x [gridy_252 | 301] lon2d = f->gridlon_252 ; [gridx_252 | 225] x [gridy_252 | 301] do n=0,npts-1 ; print surrounding pts print("n="+n+" "+city(n)+" "+lonc(n)+" "+latc(n)) print(" "+ix0(n)+" "+iy0(n)+" "+lon2d(iy0(n),ix0(n))+" "+lat2d(iy0(n),ix0(n)) ) print(" "+ix1(n)+" "+iy1(n)+" "+lon2d(iy1(n),ix1(n))+" "+lat2d(iy1(n),ix1(n)) ) print(" "+ix2(n)+" "+iy2(n)+" "+lon2d(iy2(n),ix2(n))+" "+lat2d(iy2(n),ix2(n)) ) print(" "+ix3(n)+" "+iy3(n)+" "+lon2d(iy3(n),ix3(n))+" "+lat2d(iy3(n),ix3(n)) ) end do
;------------------------------------------------------------- ; plot ;------------------------------------------------------------- wks = gsn_open_wks("ps","city") ; open a ps file rmap = True rmap@gsnMaximize = True ; maximize size rmap@gsnFrame = False ; manually advance
rmap@mpProjection = "LambertConformal" rmap@mpLambertParallel1F = lat2d@Latin1 rmap@mpLambertParallel2F = lat2d@Latin2 rmap@mpLambertMeridianF = lat2d@Lov
rmap@mpLimitMode = "Corners" ; choose range of map rmap@mpLeftCornerLatF = lat2d@corners(0) rmap@mpLeftCornerLonF = lon2d@corners(0) rmap@mpRightCornerLatF = lat2d@corners(2) rmap@mpRightCornerLonF = lon2d@corners(2)
rmap@pmTickMarkDisplayMode = "Always" ; lat/lon tick marks ;res@tmXTOn = False ; turn off top tick marks ;res@tmYROn = False ; turn off right tick marks
rmap@mpFillOn = False ; turn off map fill rmap@mpOutlineDrawOrder = "PostDraw" ; draw continental outline last rmap@mpOutlineBoundarySets = "GeophysicalAndUSStates" ; state boundaries
map = gsn_csm_map(wks,rmap) ; create a default plot
res_poly = True res_poly@gsMarkerIndex = 16 ; polymarker style res_poly@gsMarkerSizeF = 6. ; polymarker size res_poly@gsMarkerColor ="red" gsn_polymarker(wks,map,lonc,latc,res_poly) res_text = True res_text@txJust = "BottomCenter" ;"CenterCenter" ; "CenterLeft","CenterRight" res_text@txFontHeightF = 0.0075 ; size gsn_text (wks,map,city,lonc,latc+0.5,res_text) ; offset lat
; plot local RUC grid pts
res_grid = True res_grid@gsMarkerIndex = 2 ; polymarker style res_grid@gsMarkerSizeF = 6. ; polymarker size res_grid@gsMarkerColor ="green"
do n=0,npts-1 gsn_polymarker(wks,map,lon2d(iy0(n),ix0(n)),lat2d(iy0(n),ix0(n)),res_grid) gsn_polymarker(wks,map,lon2d(iy1(n),ix1(n)),lat2d(iy1(n),ix1(n)),res_grid) gsn_polymarker(wks,map,lon2d(iy2(n),ix2(n)),lat2d(iy2(n),ix2(n)),res_grid) gsn_polymarker(wks,map,lon2d(iy3(n),ix3(n)),lat2d(iy3(n),ix3(n)),res_grid) end do
frame(wks) end
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